A storage apparatus which provides a large data storage area by using a large number of storage media such as hard disk drives (hereinafter, HDDs) has been widely used. The storage apparatus provides a data storage area to a host computer (hereinafter, referred to as “host”) in which various applications run. In response to data input/output requests (hereinafter, referred to as “data I/O requests”) received from the host, the storage apparatus writes data received from the host to the storage media as well as reads data stored in the storage media and sends the data to the host.
The storage apparatus performs data processing which needs to be executed immediately in response to the data I/O request from the host described above (hereinafter, referred to as “synchronous processing”) and data processing which can be executed at a timing different from the time of receiving the data I/O request from the host (hereinafter, referred to as “asynchronous processing”). Examples of the synchronous processing include processing of writing write data to a cache memory in response to a data write request from the host and returning a write completion report to the host. On the other hand, examples of the asynchronous processing include data processing such as processing of writing data (dirty data), which has been received from the host and stored in the cache memory but has not been written to a disk yet, to the storage media (hereinafter, referred to as “intensive writing processing”) and processing for a setting change request, for example, of the storage apparatus received from a management terminal.
Heretofore, Patent Literature 1, for example, has proposed a configuration of a storage apparatus configured to execute the synchronous processing without delay by including, as processors for executing data, a processor for executing the synchronous processing and a processor for executing the asynchronous processing, separately.
Moreover, Patent Literature 2, for example, has proposed a storage apparatus including multiple processors each capable of executing the synchronous processing and the asynchronous processing. An upper limit value of the execution count of synchronous processing is set for each of the processors and each processor is configured to execute the asynchronous processing while not executing the synchronous processing.